The intrapulmonary pharmacokinetics of antimicrobial agents used to treat nontuberculous mycobacterial (NTM) pulmonary disease remains poorly characterized, limiting the optimization of dosing regimens. This study characterized the plasma and intrapulmonary pharmacokinetics of azithromycin, ethambutol, rifampicin, clofazimine, and amikacin, as well as their penetration into pulmonary lesion sites. We prospectively enrolled patients undergoing guideline-based treatment for NTM pulmonary disease who were indicated for surgical resection at a single center in Japan. Drug concentrations were measured in the plasma and lung samples and analyzed using a population pharmacokinetic model. The lung lesion site, cavity, or nodule/bronchiectatic lesion was evaluated as covariates of the lung-to-plasma partition ratios. Twenty-four patients were enrolled in the study. The estimated lung-to-plasma partition coefficients and intrapulmonary half-lives were 535-fold and 6.3 months for azithromycin, 40-fold and 2.0 months for ethambutol, 5.2-fold and 6.3 min for rifampicin, 18,800-fold and 22 years for clofazimine, 1.3-fold and 2.3 h for intravenous amikacin, and 1.3-fold and 5.0 h for inhaled amikacin, respectively. Evaluation of drug penetration into cavities and nodular/bronchiectatic lesions showed no clearly reduced concentration compared to a normal lung tissue. The intrapulmonary pharmacokinetic characteristics identified in this study provide valuable information for optimizing antimicrobial dosing regimens in the treatment of NTM pulmonary disease. Furthermore, the absence of clearly reduced drug penetration into lesion sites suggests that lesion phenotype alone may have limited value in guiding antimicrobial selection.
Current recommended front-line multidrug therapy (MDT) for Mycobacterium avium complex lung disease (MACLD) produces suboptimal outcomes. Amikacin liposome inhalation suspension (ALIS) with MDT is approved for refractory MACLD; however, clinical trial evidence in newly diagnosed MACLD is lacking.
Objectives
To evaluate efficacy and safety of ALIS with MDT in the phase 3b, randomized, double-blind, placebo-controlled superiority trial in adults newly diagnosed with MACLD who have not initiated antibiotics (ENCORE NCT04677569).
Methods
Patients (N = 425) were randomized 1:1 to receive ALIS 590 mg (n = 213) or placebo (n = 212) plus azithromycin 250 mg and ethambutol 15 mg/kg once daily for 12 months. Primary endpoint was change from baseline to month 13 in Respiratory Symptom Score (RSS). Pre-specified secondary endpoints included culture conversion (CC) at clinically important timepoints, durable culture conversion (DCC), and safety.
Results
Median age was 68.0 years, 62.8% were White, and 79.3% were female. Significantly greater improvements in RSS were observed in the ALIS versus comparator arm at 1 month post-treatment (month 13; LS mean change: 17.77 vs 14.66 points; treatment difference 3.11 points; P=0.0299), with improvements sustained at 3 months post-treatment (month 15; treatment arm difference 4.80 points; nominal P=0.0015). Significantly greater proportions of patients achieved CC by month 13 and DCC at month 15 in the ALIS arm versus comparator arm (82.4% vs 55.6% and 76.2% vs 47.6%, respectively; both P<0.0001). No new safety signals were observed.
Conclusions
ALIS with MDT was superior to the comparator arm for improving respiratory symptoms and CC in patients newly diagnosed with MACLD.
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